/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you under the Apache License, Version 2.0 (the
    * "License"); you may not use this file except in compliance
    * with the License.  You may obtain a copy of the License at
    *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing,
   * software distributed under the License is distributed on an
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   * KIND, either express or implied.  See the License for the
   * specific language governing permissions and limitations
   * under the License.
   */
  
  package org.apache.myfaces.tobago.internal.component;
  
  import org.apache.myfaces.tobago.util.FacesVersion;
  
  import javax.faces.component.UIComponentBase;
  import javax.faces.component.UIViewRoot;
  import javax.faces.context.FacesContext;
  import javax.faces.event.ComponentSystemEvent;
  import javax.faces.event.ListenerFor;
  import javax.faces.event.PostAddToViewEvent;
  import javax.faces.event.PreRenderViewEvent;
  
  @ListenerFor(systemEventClass = PostAddToViewEvent.class)
  public abstract class AbstractUIMetaLink extends UIComponentBase {
  
    @Override
    public void processEvent(final ComponentSystemEvent event) {
  
      super.processEvent(event);
  
      if (event instanceof PreRenderViewEvent) {
        addComponentResource();
      } else if (event instanceof PostAddToViewEvent) {
        if (FacesVersion.supports21() || !FacesVersion.isMyfaces()) {
          // MyFaces core is removing the component resources in head if the view will be recreated before rendering.
          // The view will be recreated because of expressions. For example  expressins in the ui:include src attribute
          // The PostAddToViewEvent will not be broadcasted in this case again.
          // A subscription to the PreRenderViewEvent avoids this problem
          // NOTE: PreRenderViewEvent can not used in myfaces prior 2.0.3 using PostAddToView for all myfaces 2.0 versions
          getFacesContext().getViewRoot().subscribeToEvent(PreRenderViewEvent.class, this);
        } else {
          addComponentResource();
        }
      }
    }
  
    private void addComponentResource() {
      final FacesContext facesContext = getFacesContext();
      final UIViewRoot root = facesContext.getViewRoot();
      root.addComponentResource(facesContext, this);
    }
  
    public abstract String getCharset();
  
    public abstract String getRev();
  
    public abstract String getHref();
  
    public abstract String getHreflang();
  
    public abstract String getRel();
  
    public abstract String getMedia();
  
    public abstract String getType();
  }